package com.example.mq.mqserver.datacenter;

import com.example.mq.common.MqException;
import com.example.mq.mqserver.core.Binding;
import com.example.mq.mqserver.core.Exchange;
import com.example.mq.mqserver.core.MSGQueue;
import com.example.mq.mqserver.core.Message;

import java.io.IOException;
import java.util.Collections;
import java.util.LinkedList;
import java.util.List;
import java.util.concurrent.ConcurrentHashMap;

/**
 * 统一管理内存中的所有数据
 * 该类提供的方法可能会在多线程环境下被使用，因此要注意线程安全问题
 */
public class MemoryDataCenter {

    // key 是 exchangeName, value 是 Exchange 对象
    private ConcurrentHashMap<String, Exchange> exchangeMap = new ConcurrentHashMap<>();

    // key 是 queueName, value 是 MSGQueue 对象
    private ConcurrentHashMap<String, MSGQueue> queueMap = new ConcurrentHashMap<>();

    // 第一个 key 是 exchangeName，第二个 key 是 queueName
    private ConcurrentHashMap<String, ConcurrentHashMap<String, Binding>> bindingsMap = new ConcurrentHashMap<>();

    // key 是 messageId, value 是 Message 对象
    private ConcurrentHashMap<String, Message> messageMap = new ConcurrentHashMap<>();

    // key 是 queueName, value 是一个 Message 的链表
    private ConcurrentHashMap<String, LinkedList<Message>> queueMessageMap = new ConcurrentHashMap<>();

    // 第一个 key 是 queueName ，第二个 key 是 messageId
    private ConcurrentHashMap<String, ConcurrentHashMap<String, Message>> queueMessageWaitAckMap = new ConcurrentHashMap<>();


    public void insertExchange(Exchange exchange){
        exchangeMap.put(exchange.getName(), exchange);
        System.out.println("[MemoryDataCenter] 新交换机添加成功！ exchangeName = " + exchange.getName());
    }

    public Exchange getExchange(String exchangeName){
        return exchangeMap.get(exchangeName);
    }

    public void deleteExchange(String exchangeName){
        exchangeMap.remove(exchangeName);
        System.out.println("[MemoryDataCenter] 交换机删除成功！ exchangeName = " + exchangeName);
    }

    public void insertQueue(MSGQueue queue){
        queueMap.put(queue.getName(), queue);
        System.out.println("[MemoryDataCenter] 新队列添加成功！ queueName = " + queue.getName());
    }

    public MSGQueue getQueue(String queueName){
        return queueMap.get(queueName);
    }

    public void deleteQueue(String queueName){
        queueMap.remove(queueName);
        System.out.println("[MemoryDataCenter] 队列删除成功！ queueName = " + queueName);
    }

    public void insertBinding(Binding binding) throws MqException {
        // 先使用 exchangeName 查一下，对应的哈希表是否存在，不存在就创建一个
//        ConcurrentHashMap<String, Binding> bindingMap = bindingsMap.get(binding.getExchangeName());
//        if(bindingMap == null){
//            bindingMap = new ConcurrentHashMap<>();
//            bindingsMap.put(binding.getExchangeName(),bindingMap);
//        }

        ConcurrentHashMap<String, Binding> bindingMap = bindingsMap.computeIfAbsent(binding.getExchangeName(),
                k -> new ConcurrentHashMap<>());

        synchronized (bindingMap){
            // 再根据 queueName 查一下，如果已经存在，就抛出异常，不存在才能插入
            if(bindingMap.get(binding.getQueueName()) != null){
                throw new MqException("[MemoryDataCenter] 绑定已经存在！ exchangeName=" + binding.getExchangeName() +
                        ", queueName=" + binding.getQueueName());
            }
            bindingMap.put(binding.getQueueName(), binding);
        }
        System.out.println("[MemoryDataCenter] 新的绑定添加成功！ exchangeName = " + binding.getExchangeName() +
                "queueName = " + binding.getQueueName());
    }

    /**
     * 获取绑定，两个版本
     * 1.根据 exchangeName 和 queueName 确定唯一一个 Binding
     * 2.根据 exchangeName 获取到所有的 binding
     */
    public Binding getBinding(String exchangeName, String queueName){
        ConcurrentHashMap<String, Binding> bindingMap = bindingsMap.get(exchangeName);
        if(null == bindingMap){
            return null;
        }
        return bindingMap.get(queueName);
    }

    public ConcurrentHashMap<String, Binding> getBindings (String exchangeName){
        return bindingsMap.get(exchangeName);
    }

    public void deleteBinding(Binding binding) throws MqException {
        ConcurrentHashMap<String, Binding> bindingMap = bindingsMap.get(binding.getExchangeName());
        if(null == bindingMap){
            //该交换机没有绑定任何队列，报错
            throw new MqException("[MemoryDataCenter] 绑定不存在！ exchangeName=" + binding.getExchangeName() +
                    ", queueName=" + binding.getQueueName());
        }
        bindingMap.remove(binding.getQueueName());
        System.out.println("[MemoryDataCenter] 绑定删除成功！ exchangeName = " + binding.getExchangeName() +
                "queueName = " + binding.getQueueName());
    }

    // 添加消息
    public void addMessage(Message message){
        messageMap.put(message.getMessageId(), message);
        System.out.println("[MemoryDataCenter] 新消息添加成功！ messageId = " + message.getMessageId());
    }

    // 根据 id 查询消息
    public Message getMessage(String messageId){
        return messageMap.get(messageId);
    }

    // 根据 id 删除消息
    public void removeMessage(String messageId){
        messageMap.remove(messageId);
        System.out.println("[MemoryDataCenter] 消息被移除！ messageId = " + messageId);
    }

    // 发送消息到指定队列
    public void sendMessage(MSGQueue queue, Message message){
        // 先根据队列的名字，找到该队列对应的消息链表
        LinkedList<Message> messages = queueMessageMap.computeIfAbsent(queue.getName(), k -> new LinkedList<>());
        // 再把数据添加到 messages 里面
        synchronized (messages){
            messages.add(message);
        }
        // 将该消息往消息中心中查一下
        addMessage(message);
        System.out.println("[MemoryDataCenter] 消息被投递到队列中！ messageId=" + message.getMessageId() );
    }

    // 从队列中获取消息
    public Message pollMessage(String queueName){
        // 根据队列名查找消息链表
        LinkedList<Message> messages = queueMessageMap.get(queueName);
        // 没找到，说明队列中没有任何消息
        if(null == messages){
            return null;
        }
        synchronized (messages){
            if(0 == messages.size()){
                return null;
            }
            // 链表中有元素，就进行头删
            Message currentMessage = messages.remove(0);
            System.out.println("[MemoryDataCenter] 消息从列表中取出！ messageId =" + currentMessage.getMessageId());
            return currentMessage;
        }
    }

    // 获取指定队列中的消息的个数
    public int getMessageCount(String queueName){
        LinkedList<Message> messages = queueMessageMap.get(queueName);
        if(null == messages){
            // 队列中没有消息
            return 0;
        }
        synchronized (messages){
            return messages.size();
        }
    }

    // 添加未确认的消息
    public void addMessageWaitAck(String queueName, Message message){
        ConcurrentHashMap<String , Message> messageHashMap = queueMessageWaitAckMap.computeIfAbsent(queueName,
                k -> new ConcurrentHashMap<>());
        messageHashMap.put(message.getMessageId(), message);
        System.out.println("[MemoryDataCenter] 消息进入待确认队列！ messageId =" + message.getMessageId());
    }

    // 删除未确认的消息
    public void removeMessageWaitAck(String queueName, String messageId){
        ConcurrentHashMap<String, Message> messageHashMap = queueMessageWaitAckMap.get(queueName);
        if(null == messageHashMap){
            return;
        }
        messageHashMap.remove(messageId);
        System.out.println("[MemoryDataCenter] 消息从待确认队列删除！ messageId = " + messageId);
    }

    //获取指定的未确认的消息
    public Message getMessageWaitAck(String queueName, String messageId){
        ConcurrentHashMap<String, Message> messageHashMap = queueMessageWaitAckMap.get(queueName);
        if(null == messageHashMap){
            return null;
        }
        return messageHashMap.get(messageId);
    }

    //从硬盘上读取数据，把硬盘中之前持久化存储的各个维度的数据恢复到内存中
    public void recovery(DiskDataCenter diskDataCenter) throws IOException, MqException, ClassNotFoundException {
        // 0. 清空之前的所有数据
        exchangeMap.clear();
        queueMap.clear();
        bindingsMap.clear();
        messageMap.clear();
        queueMessageMap.clear();
        // 1. 恢复所有的交换机数据
        List<Exchange> exchanges = diskDataCenter.selectAllExchanges();
        for(Exchange exchange : exchanges){
            exchangeMap.put(exchange.getName(), exchange);
        }
        // 2. 恢复所有的队列数据
        List<MSGQueue> queues = diskDataCenter.selectAllQueues();
        for(MSGQueue queue : queues){
            queueMap.put(queue.getName(), queue);
        }
        // 3. 恢复所有的绑定数据
        List<Binding> bindings = diskDataCenter.selectAllBindings();
        for(Binding binding : bindings){
            ConcurrentHashMap<String, Binding> bindingMap = bindingsMap.computeIfAbsent(binding.getExchangeName(),
                    k -> new ConcurrentHashMap<>());
            bindingMap.put(binding.getQueueName(), binding);
        }
        // 4. 恢复所有的消息数据
        // 遍历所有的队列，根据每个队列的名字，获取到所有的消息
        for(MSGQueue queue : queues){
            LinkedList<Message> messages = diskDataCenter.loadAllMessageFromQueue(queue.getName());
            queueMessageMap.put(queue.getName(), messages);
            for(Message message : messages){
                messageMap.put(message.getMessageId(), message);
            }
        }
    }
}
